Handbook for Sound Engineers

Digital Audio Interfacing and Networking 1499

When used with quality equipment there usually is
not a lot of advantage for fast Ethernet networks in
using cable with a rating beyond Cat5e. Future higher
speed networks, or marginal equipment on fast Ethernet
may benefit from improved cable.
Unless specified differently by the manufacturer,
most UTP has a minimum bend radius of 4 times the
cable diameter or about 1 inch.
Cat5e is inexpensive unshielded twisted pair (UTP)
data grade cable. It is very similar to ubiquitous tele-
phone cable but the pairs are more tightly twisted. It
should be noted that not all Cat5e cable is UTP. Shielded
Cat5 also exists but is rare due to its greater cost and
much shorter distance limitations than UTP Cat5e.

39.11.14.2 Distance Limitations

On fast Ethernet systems, Cat5e cable runs are limited
to 100 m due to signal radiation and attenuation
considerations. A Cat5e run in excess of 100 m may be
overly sensitive to electromagnetic interference (EMI).

39.11.15 Connectors

Cat5 cable is terminated with an RJ-45 connector.
Strictly speaking this nomenclature is incorrect since it
designates a particular telephone usage of the connector
rather than the connector itself. Since 8 position 8
contact nonkeyed modular connector is difficult to say
and write, we are stuck with the common usage of
RJ-45, Fig. 39-38.

There are two different types of contacts in RJ-45
connectors. There is the bent tyne contact, intended for
use with solid core Cat5, and then there is the aligned

tyne contact used with stranded Cat5 cable. Errors can

occur when using an incorrect cable/connector combi-

nation. Fig. 39-39 shows an end-on view of a single

contact in a modular connector. The aligned tyne

contact (on left) must be able to pierce through the

center of the wire, therefore it can only be used on

stranded wire. The bent tyne contact has the two or

three tynes offset from each other to straddle the

conductor; therefore, it can be used on solid or stranded

wire.

Cable openings in modular connectors can be shaped

for flat, oval, or round cable. Cat5 cable does not

usually fit properly into connectors made specifically

for flat telephone cable, Fig. 39-40.

Cheap modular connectors may not have proper gold

plating on the contacts, but instead only have a gold

flash. Without proper plating, the connectors may

quickly wear and corrode, causing unreliable

connections.

Figure 39-38. “RJ-45” plug. This is an 8 position 8 contact

nonkeyed modular connector originally developed for tele-

phone applications. It is the connector used for all UTP

cables in Ethernet networks.

Figure 39-39. Different style contacts found in RJ-45 plugs.

On the left is the aligned tyne contact style such as found

on original telephone connectors. Since it must pierce

through the wire, it must only be used on stranded wire.

On the right is the bent tyne contact. It has two or three-

tynes which are offset from each other and straddle the

conductor. As a result it can be used on either stranded or

solid conductor wire.

Figure 39-40. Different style cable openings found in RJ-45

plugs. On the left is the opening for flat cable such as

found on original telephone connectors. On the right is the

opening for round cable needed for Cat 5 cable.